Is there a way to see all sponsored tags?
Short of scanning all the tags page, of course.
BTW, I find this way of advertising pretty much aesthetic.
No, but it really should. I really like this kind of sponsoring. Branding without disturbing. Companies that understands that should be honored with some kind of listing or search-option.
One easy solution is to add an extra tab (or link) under 'Tag'-page. The listing could be a really simple one, only the sponsors and their tags. I think that would be a great way to show us who the sponsors are and in a way thank them for supporting the community, Jeff and everyone else that benefits from their money.